Surgical instrument with non-contact electrical coupling

ABSTRACT

A surgical instrument includes a reusable base component including a handle and an electrically activatable modular component removably coupled to the base component. The modular component includes an end effector operable from the handle to treat tissue. The end effector is responsive to manipulation of the handle. A first energy storage component is disposed onboard the base component and is electrically coupled to a source of electricity. A second energy storage component is disposed onboard the modular component and is electrically insulated from the first energy storage component. The second energy storage component is arranged such that a current may be selectively induced in the modular component by delivery of electrical energy to the first energy storage component.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No. 12/758,524, filed Apr. 12, 2010, the contents of which is hereby incorporated by reference in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates generally the field of reusable surgical instruments. In particular, the disclosure relates electrical couplings for instruments having separable and replaceable components to provide clean, sterile or refurbished surfaces in each instance of use.

2. Background of Related Art

Instruments such as electrosurgical forceps are commonly used in open and endoscopic surgical procedures to coagulate, cauterize and seal tissue. Such forceps typically include a pair of jaws that can be controlled by a surgeon to grasp targeted tissue, such as, e.g., a blood vessel. The jaws may be approximated to apply a mechanical clamping force to the tissue, and are associated with at least one electrode surface to permit the delivery of electrosurgical energy to the tissue. The combination of the mechanical clamping force and the electrosurgical energy has been demonstrated to join adjacent layers of tissue captured between the jaws. When the adjacent layers of tissue include the walls of a blood vessel, sealing the tissue may result in hemostasis. Thereafter, the sealed tissue may be transected by advancing a knife through the jaws. A detailed discussion of the use of an electrosurgical forceps may be found in U.S. Pat. No. 7,255,697 to Dycus et al.

In use, various tissue-contacting components of an electrosurgical forceps tend to become contaminated or degraded. For example, electrodes may become contaminated as portions of the treated tissue adhere to the tissue-contacting surfaces of the electrodes. Also, a knife blade may become dull and less effective in transecting sealed tissue after repeated use, even in a single surgical procedure. In order to provide clean electrodes and a sharp knife for a particular surgical procedure, a brand new instrument is often used. Once the procedure is complete, the used instrument is discarded.

Instruments that are reusable for multiple procedures reduce the instrumentation costs per procedure. Some reusable forceps include a reusable component adapted for persistent use coupled to a removable and replaceable component adapted for limited use. The reusable component may include, for example, a control element such as a handle that remains primarily outside the surgical field. The handle may be constructed ruggedly to sustain regular and recurring usage in numerous surgical procedures. The removable and replaceable component may include a tool element, such as an end effector containing the delicate and tissue-contacting wear surfaces. Replacing a worn end effector to refurbish an instrument provides refreshed surfaces with minimal waste.

Providing replaceable components for a reusable electrosurgical forceps, however, presents various challenges. For example, many of these instruments require arduous disassembly and reassembly procedures to ensure proper electrical continuity is provided between the reusable and replaceable components. Also, electrical couplings on the reusable component may be difficult to clean.

SUMMARY

The present disclosure describes a surgical instrument for treating tissue. The instrument includes a reusable base component with a handle assembly and an electrically-activated modular component removably coupled to the base component. The modular component includes an end effector operable from the handle assembly to treat tissue, and the end effector is responsive to manipulation of the handle assembly to move between first and second configurations. A first energy storage component is disposed onboard the base component, and the first energy storage component is electrically coupled to a source of electricity. A second energy storage component is disposed onboard the modular component. The second energy storage component is electrically insulated from the first energy storage component and is arranged with respect to the first energy storage component such that a current may be selectively induced in the modular component by delivery of electrical energy to the first energy storage component.

The first energy storage component may include a first inductive coil and the second energy storage component may include a second inductive coil. The second inductive coil may be inductively coupled to the first inductive coil such that a current is induced in the second coil in response to a current flow in the first coil.

The source of electricity may be an electrosurgical generator, and the modular component may include at least one electrode. The electrode may be electrically coupled to the second coil and configured for delivering electrosurgical energy to tissue.

The modular component may include pair of opposing jaw members, and one or both of the jaw member may be movable between an open configuration wherein the jaw members are substantially spaced for receiving tissue and a closed configuration wherein the jaw members are closer together for clamping tissue therebetween. The end effector may include a sensor for detecting a parameter of the tissue treatment, and the sensor may be powered by the induced current in the second coil. The sensor may be a gap sensor configured to detect a separation distance between the opposing jaw members.

The first energy storage component may include a first capacitor having a pair of conductive plates separated by a dielectric material. The second energy storage component may include a second capacitor having a pair of conductive plates arranged on opposite sides of the first capacitor. Each of the conductive plates of the second capacitor may be separated from a conductive plate of the first capacitor by a dielectric material. The conductive plates of the second capacitor may be arranged on a respective opposing jaw member.

According to another aspect of the disclosure, a modular end effector for a surgical instrument includes an electrically-activated component and an inductor coil electrically coupled to the electrically-activated component. The end effector includes a contactless mechanical interface configured to removably couple the end effector to a corresponding interface on a base component of the surgical instrument. The mechanical interface is electrically isolated from the electrically-activated component.

The end effector may include a pair of opposing jaw members, and one or both of the jaw members may be movable between an open configuration wherein the jaw members are substantially spaced for receiving tissue and a closed configuration wherein the jaw members are closer together for clamping tissue therebetween. The electrically-activated component may include an electrode disposed on an opposed clamping surface of one of the jaw members, and the contactless mechanical interface may include a linkage for receiving reciprocal motion from the base component. The linkage may be operable to move the at least one of the pair of jaw members between the open configuration and the closed configuration.

According to another aspect of the disclosure, a surgical instrument includes a reusable base component with a handle assembly and an elongated tube extending distally from the handle assembly. An electrically-activated modular component is removably coupled to the base component, and the modular component includes a pair of jaw members operable from the handle assembly and configured to move between an open configuration wherein the jaw members are substantially spaced for receiving tissue and a closed configuration wherein the jaw members are closer together for clamping tissue. A first capacitor plate is operatively associated with the elongated tube, and a second capacitor plate is operatively associated with one of the jaw members. The second capacitor plate forms a capacitor with the first capacitor plate to capacitively couple the base component and the modular component.

The first capacitor plate may be electrically coupled to a source of electrosurgical energy, the second capacitor plate may be electrically coupled to an electrode configured to deliver the electrosurgical energy to tissue. A pair of capacitor plates may be operatively associated with the elongated tube, and each of the jaw members may include a capacitor plate forming a respective capacitor with a respective capacitor plate of the elongated tube.

The one of the jaw members may include a pair of capacitor plates straddling the first capacitor plate on the elongated tube. The pair of capacitor plates of the one of the jaw members may define legs of a generally U-shaped conductive portion of the first jaw member.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the detailed description of the embodiments given below, serve to explain the principles of the disclosure.

FIG. 1 is a perspective view of an endoscopic surgical instrument in accordance with an embodiment of the present disclosure having modular jaw members inductively coupled to a distal end of an elongated shaft;

FIG. 2 is an enlarged, perspective view of a distal end of the instrument of FIG. 1 depicting the modular jaw members separated from the elongated shaft;

FIG. 3 is a perspective view of an alternate embodiment of an instrument in accordance with the present disclosure having a modular end effector separated from an elongated shaft;

FIG. 4A is a perspective view of an alternate embodiment of an instrument in accordance with the present disclosure having modular jaw members for capacitive coupling with an elongated shaft;

FIG. 4B is a cross-sectional view of the modular jaw members of FIG. 4A capacitively coupled to the elongated shaft;

FIG. 4C is a schematic view of a current path through tissue captured between the modular jaw members of FIG. 4A;

FIG. 5 is a perspective view of an alternate embodiment of modular jaw members configured for capacitive coupling with an elongated shaft wherein multiple plates are employed; and

FIG. 6 is an alternate embodiment of a surgical instrument in accordance with the present disclosure configured for use in open surgical procedures.

DETAILED DESCRIPTION

Referring initially to FIG. 1, an embodiment of an electrosurgical instrument 10 is depicted. The instrument 10 includes a handle assembly 12, an end effector 14 and an elongated shaft 16 therebetween. A surgeon may manipulate the handle assembly 12 to remotely control the end effector 14 through the elongated shaft 16. This configuration is typically associated with instruments for use in laparoscopic or endoscopic surgical procedures. Various aspects of the present disclosure may also be practiced with traditional open instruments (see FIG. 5), and in connection with endoluminal procedures as well.

The instrument 10 is coupled to a source of electrosurgical energy, e.g., an electrosurgical generator 18. The generator 18 may include devices such as the LIGASURE™ Vessel Sealing Generator and the Force Triad™ Generator as sold by Covidien. A cable 20 extends between the handle assembly 12 and the generator 18, and includes a connector 22 for coupling the instrument 10 to the generator 18. The connector 22 includes two prong members 22 a and 22 b that are dimensioned to mechanically and electrically connect the instrument 10 to opposite terminals, e.g., positive or active (+) and negative or return (−) terminals associated with the generator 18. Thus, bipolar energy may be provided through the instrument 10. Alternatively, the instrument 10 may be configured for delivering monopolar energy to the tissue. In a monopolar configuration, the instrument 10 delivers electrosurgical energy from an active terminal, e.g. (+), while a return pad (not shown) is placed generally beneath a patient and provides a return path to the opposite terminal, e.g. (−), of the generator 18.

To control the end effector 14, the handle assembly 12 includes a stationary handle 24 and movable handle 26. The movable handle 26 may be separated and approximated relative to the stationary handle 24 to respectively open and close the end effector 14. A trigger 30 is also disposed on the handle assembly 12, and is operable to extend and retract a knife 76 (FIG. 3) through the end effector 14. A footswitch (not shown) may be provided to initiate and terminate the delivery of electrosurgical energy to the end effector 14.

Referring now to FIG. 2, end effector 14 includes upper and lower jaw members 32 and 34. Each of the modular jaw members 32, 34 is coupled to the elongated shaft 16 about a pivot pin 36. The jaw members 32, 34 include respective proximal flanges 38, 40 extending into a bifurcated distal end of the elongated shaft 16, where a respective bore 38 a, 40 a engages the pivot pin 36. The proximal flanges 38, 40 are operatively associated with the movable handle 26 (FIG. 1) to open and close the jaw members 32, 34. The jaw members 32, 34 are movable between an open configuration where the jaw members 32, 34 are substantially spaced to receive tissue and a closed configuration where the jaw members 32, 34 are closer together to clamp the tissue therebetween. Retraction of the movable handle 26 induces the jaw members 32, 34 to move to the open configuration and separation of the movable handle 26 from the stationary handle 24 induces the jaw members 32, 34 to move to the closed configuration.

Various mechanisms may be provided to operatively associate the movable handle 26 with the proximal flanges 38, 40. For example, the movable handle 26 may be coupled to a reciprocating member (not shown) that extends through the elongated shaft 16 as described in commonly owned U.S. Pat. No. 7,255,697 to Dycus et al. The reciprocating member may engage cam slots (not shown) on each of the proximal flanges 38, 40 to change the position of both of the jaw members 32, 34 relative to the elongated shaft. This type of construction induces bilateral jaw motion. Other unilateral constructions are also envisioned in which only one jaw member 32, 34 moves with respect to the elongated shaft.

When clamped about tissue, the jaw members 32, 34 may deliver electrosurgical energy to the tissue through a pair of opposed electrodes 42, 44. The electrodes 42, 44 are configured to selectively apply an effective amount of pressure and electrosurgical energy to the tissue. The opposed electrodes are associated with opposite electrical potentials (+), (−) to permit an electrosurgical current to flow through the tissue situated between the jaw members 32, 34 to effect a tissue seal.

The modular jaw members 32 and 34 are selectively removable from the elongated shaft 16 to facilitate replacement the jaw members 32, 34 following a surgical procedure. Replacement of the jaw members 32, 34 may serve to refurbish the instrument 10 for subsequent use. The pivot pin 36 may be spring loaded to retain the flanges 38 and 40 within the bifurcated distal end of the elongated shaft 16 when the instrument 10 is in use. Following an electrosurgical procedure, the spring loaded pivot pin 36 may be manipulated to release the used jaw members 32, 34 without requiring a cumbersome disassembly process. Thereafter, the pivot pin 36 may snap into a set of bores 38 a, 40 a of a clean, new or refurbished set of jaw members 32, 34.

In the illustrated embodiment, when the jaw members 32, 34 are connected to the elongated shaft, a contactless electrical coupling is established. The proximal flange 40 of lower jaw member 34 is inductively coupled to the elongated shaft 16 through a pair of spiral coils 48, 52. The spiral coils 48, 52 form inductors, which store energy by generating a magnetic field when an electrical current is passed therethrough. The first coil 48 is disposed onboard the elongated shaft 16, which forms part of a reusable base component of the instrument 10. The first coil 48 is electrically coupled to the two prongs 22 a, 22 b of the connector 22 (FIG. 1) through respective lead wires 48 a, 48 b extending through the instrument 10. The two lead wires 48 a, 48 b may be associated with the opposite electrical potentials of the prongs 22 a (+), 22 b (−). The second coil 52 is disposed on board the modular jaw member 34, which forms a replaceable component of the instrument 10. The second coil 52 is electrically coupled to the two electrodes 42 (+) and 44 (−) of opposite electrical potential.

The coils 48, 52 are constructed of an appropriate electrically conductive material, such as copper or stainless steel wire. The coils 48, 52 are separated by an electrically insulative material such that no direct contact exists between the coils 48, 52. One or both of the elongated shaft 16 and the proximal flange 40 of the lower jaw member 34 may be constructed of an insulative material such as a ceramic or reinforced plastic that contains the respective coil 48, 52. The insulative material protects the coils 48, 52 from mechanical damage, and may form a flat interface on the exterior of the respective component 16, 40 that may be cleaned without undue difficulty.

The coils 48, 52 are arranged such that when the lower jaw member 34 is installed, the coils 48, 52 are axially aligned, and face-to-face in parallel planes. The two coils 48, 52 are spatially as close to one another as is practical since inductive coupling is most effective at short distances. In use, a current is supplied by the electrosurgical generator 18 (FIG. 1) to the first coil 48. The current in the first coil 48 generates a magnetic field passing through the second coil 52. The magnetic field induces a current in the second coil 52 that is used to power the electrodes 42, 44.

Referring now to FIG. 3, an alternate embodiment of an instrument 60 includes a reusable base component 62 and a removable modular component 64. The base component 62 includes a first elongated shaft portion 66 a extending from a handle assembly 12 (see FIG. 1), and the modular component 64 includes a second elongated shaft component 66 b extending to an end effector 68. The two elongated shaft portions 66 a, 66 b may be mechanically fastened to one another to permit mechanical motion of jaw members 72, 74 between open and closed configurations and advancement and retraction of an optional reciprocating knife blade 76 through the lower jaw member 74.

Advancement of the reciprocating knife 76 permits the transaction of tissue, particularly once the tissue has been sealed. To facilitate the mechanical motion of the jaw members 72, 74 and/or the knife blade 76, the modular component 64 includes a first linkage 77 a for receiving reciprocal motion from a corresponding second linkage 77 b on the base component 62. The first linkage 77 a may be directly coupled to the knife 76 such that reciprocal motion of the first linkage 77 a induces a corresponding reciprocal motion in the knife 76. Alternatively or additionally, the reciprocal motion of the first linkage may be converted to pivotal motion of the jaw members 72, 74 through the use of cam surfaces (not shown) or other conventional mechanisms. The second linkage 77 b extends to the handle assembly 12 (FIG. 1) and may receive reciprocal motion therefrom.

An electrical coupling between the modular component 64 and the base component 62 may be established by inductive coupling. The base component 62 includes a first coil 78 electrically coupled to the opposite poles of electrosurgical generator 18 (FIG. 1). The modular component includes a second coil 80 that may be coupled to electrodes 82 and 84. First and second coils 78, 80 are longitudinally arranged in respective elongated shaft portions 66 a, 66 b. The elongated shaft portions 66 a, 66 b provide ample length for a significant number of coils. The coils 78, 80 are laterally separated from one another. Other configurations are envisioned, such as a coaxial configuration wherein one coil is situated longitudinally within the other. This type of electrical coupling permits a contactless mechanical interface to be established between the removable component 64 and the base component 62. The mechanical interface may be contactless in that electricity is not transmitted through any of the mechanically engaging surfaces such that the mechanical interface is electrically isolated from the electrodes 82, 84.

In addition to the electrodes 82, 84, other electrical devices may be included on the modular component 64 to be powered by a current flowing through the second coil 80. For example, a gap sensor 86 is included on the lower jaw member 74. The gap sensor 86 is configured to sense the separation or “gap distance” between the jaw members 72, 74. An appropriate gap distance for generating an effective tissue seal may be between about 0.001 inches and about 0.006 inches. A gap distance between about 0.002 inches and about 0.003 inches may be preferred in some instances. The gap sensor 86 may include any suitable sensor such as optical sensor, and may receive power and communicate data with the electrosurgical generator 18 through the inductive coupling. An appropriate gap sensor is described in commonly owned U.S. Patent Application Publication No. 2009/0204114 to Odom.

Referring now to FIG. 4A, an alternate embodiment of an instrument 100 includes modular jaw members 102, 104 configured for non-contact, capacitive coupling with a base component 106. The base component 106 includes a pair of electrically conductive plates 110 a, 110 b disposed at a distal end of an elongated shaft 112. The plates 110 a, 110 b are coupled to the electrosurgical generator 18 (FIG. 1) such that a first conductive plate 110 a is coupled to a first terminal of the generator, e.g. active (+), and a second conductive plate 110 b is coupled to a second terminal, e.g. return (−). The conductive plates 110 a, 110 b are separated by an electrically insulative, dielectric material 114. A pair of dielectric plates 116 a and 116 b are disposed laterally exterior to the conductive plates 110 a, 110 b.

A proximal flange 118 of the upper jaw member 102 includes a flat-plate electrically conductive portion 120 adjacent a structural body portion 122. Similarly, a proximal flange 124 of the lower jaw member 104 includes a flat-plate electrically conductive portion 126 adjacent a structural body portion 128. The conductive plate portions 120, 126 are in electrical communication with respective electrodes 132, 134.

The modular jaw members 102, 104 may be assembled to the base component 106 as depicted in FIG. 4B. The distal end of elongated shaft 112 is interposed between the electrically conductive plates 120, 126 of the jaw members 102, 104. The dielectric plate 116 a is interposed between conductive plates 110 a and 120 to define a first parallel plate capacitor 136. The conductive plate 120 of the upper jaw member 102 may thus be capacitively coupled to the base component 106. The dielectric plate 116 b is similarly interposed between conductive plates 110 b and 126 to define a second capacitor 138. The conductive plate 126 of the lower jaw member 104 may thus be capacitively coupled to the base component 106.

When the modular jaw members 102, 104 are assembled to the base component 106 and tissue “t” is captured between the electrodes 132, 134, an electrosurgical current “I” may be induced through the tissue “t” as indicated in FIG. 4C. Electrosurgical energy, such as electrosurgical current “I” at a predetermined output frequency and power may pass from a first terminal, e.g. an active terminal (+), of the generator 18 through the first capacitor 136 to upper jaw member 102. The current “I” is transmitted through the active electrode 132 and the tissue “t” to return electrode 134. The current “I” returns through second capacitor 138 to a second terminal, e.g., a return terminal (−), of the generator 18.

Referring now to FIG. 5, an alternate embodiment of a modular jaw member 152 is configured for capacitive coupling to a base shaft 154. The modular jaw member 154 includes an electrically conductive plate 156 and an electrically conductive U-shaped portion 158 having a pair of generally flat legs or plates 158 a and 158 b. The conductive plate 156 and U-shaped portion 158 are disposed in an insulative structural body portion 160, and may be electrically coupled to an electrode (not shown) configured to deliver electrosurgical energy to tissue. The base shaft 154 includes first and second conductive plates 162, 164 each electrically coupled to an active terminal (+) of electrosurgical generator 18. The conductive plates 162, 164 are disposed in an insulative body portion 166.

The modular jaw member 152 may be assembled to the base shaft 154 such that the U-shaped portion 158 of jaw member 152 straddles the first conductive plate 162 of the shaft 164. In the assembled configuration, the first conductive plate 162 of the shaft 154 forms a parallel plate capacitor with each of the legs 158 a, 158 b of the U-shaped portion 158. Additionally, the second conductive plate 164 of the shaft 154 forms a parallel plate capacitor with conductive plate 156 of the modular jaw member 152.

A similar construction may be defined for an opposing jaw member (not shown) configured for capacitive coupling to a return terminal (−), of the generator 18. Since each of the terminals (+), (−) of the generator 18 are capacitively coupled a respective jaw member, e.g., jaw member 152, through plates, e.g., 156, 158 a, 158 b, 162, 164 forming multiple capacitors, a greater current may be induced through tissue.

With regard to FIG. 6, a forceps 200 configured for use in various open surgical procedures may also incorporate many of the features described above. Forceps 200 includes a pair of opposing elongated shafts 212 a and 212 b having an end effector assembly 230 attached to the distal ends 216 a and 216 b thereof, respectively. End effector assembly 230 is similar in design to end effector assembly 14 described above with reference to FIG. 1. End effector assembly 230 includes pair of opposing jaw members 232 and 234 that are pivotably connected about a pivot pin 265, and which are movable relative to one another to grasp tissue.

Each shaft 212 a and 212 b includes a handle 215 and 217, respectively, disposed at the proximal end 214 a and 214 b thereof which each define a finger hole 215 a and 217 a, respectively, therethrough for receiving a finger of the clinician. Finger holes 215 a and 217 a facilitate movement of the shafts 212 a and 212 b relative to one another which, in turn, pivot the jaw members 232 and 234 from an open position wherein the jaw members 232 and 234 are disposed in spaced relation relative to one another to a clamping or closed position wherein the jaw members 232 and 234 cooperate to grasp tissue therebetween.

An electrosurgical cable 268 couples the instrument 200 to a source of electrosurgical energy, and conductive pathways 270 are provided to transmit electrosurgical energy to the jaw members 232, 234. A knife trigger 280 is provided to induce a knife (not shown) to transect tissue captured between the jaw members 232, 234.

The jaw members 232 and 234 may be configured as modular and selectively removable components separable from the rest of the forceps 200. The jaw members may be coupled with a contactless electrical interface as described above to connect the jaw members 232, 234 to the conductive pathways 270. For example, an inductive coupling as described above with reference to FIGS. 2 and 3 may be provided, or a capacitive coupling interface as described above with reference to FIGS. 4A and 4B may be selected.

Although the foregoing disclosure has been described in some detail by way of illustration and example, for purposes of clarity or understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the appended claims. 

1. A surgical instrument, comprising: a reusable base component, the base component including a handle assembly; an electrically-activated modular component removably coupled to the base component, the modular component including an end effector operable from the handle assembly to treat tissue, the end effector responsive to manipulation of the handle assembly to move between first and second configurations; a first energy storage component disposed onboard the base component, the first energy storage component electrically coupled to a source of electricity, the first energy storage component includes a first capacitor having a pair of conductive plates separated by a dielectric material; and a second energy storage component onboard the modular component, the second energy storage component electrically insulated from the first energy storage component and arranged with respect to the first energy storage component such that a current may be selectively induced in the modular component by delivery of electrical energy to the first energy storage component the second energy storage device includes a second capacitor having a pair of conductive plates arranged on opposite sides of the first capacitor, each of the conductive plates of the second capacitor separated from a conductive plate of the first capacitor by a dielectric material. 2-8. (canceled)
 9. The surgical instrument according to claim 1, wherein each of the conductive plates of the second capacitor are arranged on a respective opposing jaw member. 10-13. (canceled)
 14. A surgical instrument, comprising: a reusable base component, the base component including a handle assembly and an elongated tube extending distally therefrom; an electrically-activated modular component removably coupled to the base component, the modular component including a pair of jaw members operable from the handle assembly and configured to move between an open configuration wherein the jaw members are substantially spaced for receiving tissue and a closed configuration wherein the jaw members are closer together for clamping tissue therebetween; a first capacitor plate operatively associated with the elongated tube; and a second capacitor plate operatively associated with one of the jaw members, the second capacitor plate forming a capacitor with the first capacitor plate to capacitively couple the base component and the modular component.
 15. The surgical instrument according to claim 14, wherein the first capacitor plate is electrically coupled to a source of electrosurgical energy, and wherein the second capacitor plate is electrically coupled to an electrode configured to deliver the electrosurgical energy to tissue.
 16. The surgical instrument according to claim 14, wherein a pair of capacitor plates is operatively associated with the elongated tube, and wherein each of the jaw members includes a capacitor plate disposed thereon forming a respective capacitor with a respective capacitor plate of the elongated tube.
 17. The surgical instrument according to claim 14, wherein the one of the jaw members includes a pair of capacitor plates disposed thereon straddling the first capacitor plate.
 18. The surgical instrument according to claim 17, wherein the pair of capacitor plates of the one of the jaw members define legs of a generally U-shaped conductive portion of the first jaw member. 